This invention relates to the field of human actuated control devices such as the joystick control or control stick or control column used in video games, aircraft flight surface control, construction machinery maneuvering and in other human operated apparatus.
The coupling system by which information from an aircraft pilot is transmitted to the aircraft control surfaces and the resulting response of the aircraft to control surface position changes has reached a refined state of evolution. In most present-day commercial and military aircraft, for example, the use of hydraulic or other power assistance arrangements is routine and the achievement of realistic stick "feel"--even in the presence of this power assistance has been enhanced with each new generation of aircraft.
With respect to control stick to aircraft dynamic response for example, it is now recognized that a degree of dynamic instability or system overshoot followed by damped oscillation can be desirable in high-performance aircraft such as a military fighter. In the F-16 aircraft currently used by the U.S. Air Force, for example, in the roll axis mode, the roll dynamics are intentionally made to be slightly unstable in this manner in order to achieve a quick response to the human pilot commands. Fighter pilots are known to prefer this type of pilot-to-aircraft interaction as a result of a desire to have the aircraft be extremely sensitive to commands. Another example of such controls is found in present-day helicopters wherein the control stick system dynamics are inherently unstable but also provide the helicoper with the capability for rapid maneuvering. In the present invention, this interface between the human operator and the controlled apparatus is considered in terms of the control stick transfer functions and mechanical impedances.